"""
Sleep Module Router (v9d Phase 2b)

Endpoints:
- CRUD: list, create/upsert, update, delete
- Stats: 7-day average, trends, phase distribution, sleep debt
- Correlations: sleep ↔ resting HR, training, weight (Phase 2e)
"""
from fastapi import APIRouter, Depends, HTTPException, UploadFile, File
from pydantic import BaseModel
from typing import Literal
from datetime import datetime, timedelta
import csv
import io
import json

from auth import require_auth
from db import get_db, get_cursor

router = APIRouter(prefix="/api/sleep", tags=["sleep"])

# ── Models ────────────────────────────────────────────────────────────────────

class SleepCreate(BaseModel):
    date: str  # YYYY-MM-DD
    bedtime: str | None = None  # HH:MM
    wake_time: str | None = None  # HH:MM
    duration_minutes: int
    quality: int | None = None  # 1-5
    wake_count: int | None = None
    deep_minutes: int | None = None
    rem_minutes: int | None = None
    light_minutes: int | None = None
    awake_minutes: int | None = None
    note: str = ""
    source: Literal['manual', 'apple_health', 'garmin'] = 'manual'

class SleepResponse(BaseModel):
    id: int
    profile_id: str
    date: str
    bedtime: str | None
    wake_time: str | None
    duration_minutes: int
    duration_formatted: str
    quality: int | None
    wake_count: int | None
    deep_minutes: int | None
    rem_minutes: int | None
    light_minutes: int | None
    awake_minutes: int | None
    sleep_segments: list | None
    sleep_efficiency: float | None
    deep_percent: float | None
    rem_percent: float | None
    note: str
    source: str
    created_at: str

class SleepStatsResponse(BaseModel):
    avg_duration_minutes: float
    avg_quality: float | None
    total_nights: int
    nights_below_goal: int
    sleep_goal_minutes: int

class SleepDebtResponse(BaseModel):
    sleep_debt_minutes: int
    sleep_debt_formatted: str
    days_analyzed: int
    sleep_goal_minutes: int

# ── Helper Functions ──────────────────────────────────────────────────────────

def format_duration(minutes: int) -> str:
    """Convert minutes to 'Xh Ymin' format."""
    hours = minutes // 60
    mins = minutes % 60
    return f"{hours}h {mins}min"

def calculate_sleep_efficiency(duration_min: int, awake_min: int | None) -> float | None:
    """Sleep efficiency = duration / (duration + awake) * 100."""
    if awake_min is None or awake_min == 0:
        return None
    total = duration_min + awake_min
    return round((duration_min / total) * 100, 1) if total > 0 else None

def calculate_phase_percent(phase_min: int | None, duration_min: int) -> float | None:
    """Calculate phase percentage of total duration."""
    if phase_min is None or duration_min == 0:
        return None
    return round((phase_min / duration_min) * 100, 1)

def row_to_sleep_response(row: dict) -> SleepResponse:
    """Convert DB row to SleepResponse."""
    return SleepResponse(
        id=row['id'],
        profile_id=row['profile_id'],
        date=str(row['date']),
        bedtime=str(row['bedtime']) if row['bedtime'] else None,
        wake_time=str(row['wake_time']) if row['wake_time'] else None,
        duration_minutes=row['duration_minutes'],
        duration_formatted=format_duration(row['duration_minutes']),
        quality=row['quality'],
        wake_count=row['wake_count'],
        deep_minutes=row['deep_minutes'],
        rem_minutes=row['rem_minutes'],
        light_minutes=row['light_minutes'],
        awake_minutes=row['awake_minutes'],
        sleep_segments=row['sleep_segments'],
        sleep_efficiency=calculate_sleep_efficiency(row['duration_minutes'], row['awake_minutes']),
        deep_percent=calculate_phase_percent(row['deep_minutes'], row['duration_minutes']),
        rem_percent=calculate_phase_percent(row['rem_minutes'], row['duration_minutes']),
        note=row['note'] or "",
        source=row['source'],
        created_at=str(row['created_at'])
    )

# ── CRUD Endpoints ────────────────────────────────────────────────────────────

@router.get("")
def list_sleep(
    limit: int = 90,
    session: dict = Depends(require_auth)
):
    """List sleep entries for current profile (last N days)."""
    pid = session['profile_id']

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("""
            SELECT * FROM sleep_log
            WHERE profile_id = %s
            ORDER BY date DESC
            LIMIT %s
        """, (pid, limit))
        rows = cur.fetchall()

    return [row_to_sleep_response(row) for row in rows]

@router.get("/by-date/{date}")
def get_sleep_by_date(
    date: str,
    session: dict = Depends(require_auth)
):
    """Get sleep entry for specific date."""
    pid = session['profile_id']

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("""
            SELECT * FROM sleep_log
            WHERE profile_id = %s AND date = %s
        """, (pid, date))
        row = cur.fetchone()

    if not row:
        raise HTTPException(404, "No sleep entry for this date")

    return row_to_sleep_response(row)

@router.post("")
def create_sleep(
    data: SleepCreate,
    session: dict = Depends(require_auth)
):
    """Create or update sleep entry (upsert by date)."""
    pid = session['profile_id']

    # Convert empty strings to None for TIME fields
    bedtime = data.bedtime if data.bedtime else None
    wake_time = data.wake_time if data.wake_time else None

    # Plausibility check: sleep phases (deep+rem+light) should sum to duration
    # Note: awake_minutes is NOT part of sleep duration (tracked separately)
    if any([data.deep_minutes, data.rem_minutes, data.light_minutes]):
        sleep_phase_sum = (data.deep_minutes or 0) + (data.rem_minutes or 0) + (data.light_minutes or 0)
        diff = abs(data.duration_minutes - sleep_phase_sum)
        if diff > 5:
            raise HTTPException(
                400,
                f"Plausibilitätsprüfung fehlgeschlagen: Schlafphasen-Summe ({sleep_phase_sum} min) weicht um {diff} min von Schlafdauer ({data.duration_minutes} min) ab. Max. Toleranz: 5 min. Hinweis: Wachphasen werden nicht zur Schlafdauer gezählt."
            )

    with get_db() as conn:
        cur = get_cursor(conn)

        # Upsert: INSERT ... ON CONFLICT DO UPDATE
        cur.execute("""
            INSERT INTO sleep_log (
                profile_id, date, bedtime, wake_time, duration_minutes,
                quality, wake_count, deep_minutes, rem_minutes, light_minutes,
                awake_minutes, note, source, updated_at
            ) VALUES (
                %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, CURRENT_TIMESTAMP
            )
            ON CONFLICT (profile_id, date) DO UPDATE SET
                bedtime = EXCLUDED.bedtime,
                wake_time = EXCLUDED.wake_time,
                duration_minutes = EXCLUDED.duration_minutes,
                quality = EXCLUDED.quality,
                wake_count = EXCLUDED.wake_count,
                deep_minutes = EXCLUDED.deep_minutes,
                rem_minutes = EXCLUDED.rem_minutes,
                light_minutes = EXCLUDED.light_minutes,
                awake_minutes = EXCLUDED.awake_minutes,
                note = EXCLUDED.note,
                source = EXCLUDED.source,
                updated_at = CURRENT_TIMESTAMP
            RETURNING *
        """, (
            pid, data.date, bedtime, wake_time, data.duration_minutes,
            data.quality, data.wake_count, data.deep_minutes, data.rem_minutes,
            data.light_minutes, data.awake_minutes, data.note, data.source
        ))

        row = cur.fetchone()
        conn.commit()

    return row_to_sleep_response(row)

@router.put("/{id}")
def update_sleep(
    id: int,
    data: SleepCreate,
    session: dict = Depends(require_auth)
):
    """Update existing sleep entry by ID."""
    pid = session['profile_id']

    # Convert empty strings to None for TIME fields
    bedtime = data.bedtime if data.bedtime else None
    wake_time = data.wake_time if data.wake_time else None

    # Plausibility check: sleep phases (deep+rem+light) should sum to duration
    # Note: awake_minutes is NOT part of sleep duration (tracked separately)
    if any([data.deep_minutes, data.rem_minutes, data.light_minutes]):
        sleep_phase_sum = (data.deep_minutes or 0) + (data.rem_minutes or 0) + (data.light_minutes or 0)
        diff = abs(data.duration_minutes - sleep_phase_sum)
        if diff > 5:
            raise HTTPException(
                400,
                f"Plausibilitätsprüfung fehlgeschlagen: Schlafphasen-Summe ({sleep_phase_sum} min) weicht um {diff} min von Schlafdauer ({data.duration_minutes} min) ab. Max. Toleranz: 5 min. Hinweis: Wachphasen werden nicht zur Schlafdauer gezählt."
            )

    with get_db() as conn:
        cur = get_cursor(conn)

        cur.execute("""
            UPDATE sleep_log SET
                date = %s,
                bedtime = %s,
                wake_time = %s,
                duration_minutes = %s,
                quality = %s,
                wake_count = %s,
                deep_minutes = %s,
                rem_minutes = %s,
                light_minutes = %s,
                awake_minutes = %s,
                note = %s,
                updated_at = CURRENT_TIMESTAMP
            WHERE id = %s AND profile_id = %s
            RETURNING *
        """, (
            data.date, bedtime, wake_time, data.duration_minutes,
            data.quality, data.wake_count, data.deep_minutes, data.rem_minutes,
            data.light_minutes, data.awake_minutes, data.note, id, pid
        ))

        row = cur.fetchone()
        if not row:
            raise HTTPException(404, "Sleep entry not found")

        conn.commit()

    return row_to_sleep_response(row)

@router.delete("/{id}")
def delete_sleep(
    id: int,
    session: dict = Depends(require_auth)
):
    """Delete sleep entry."""
    pid = session['profile_id']

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("""
            DELETE FROM sleep_log
            WHERE id = %s AND profile_id = %s
        """, (id, pid))
        conn.commit()

    return {"deleted": id}

# ── Stats Endpoints ───────────────────────────────────────────────────────────

@router.get("/stats")
def get_sleep_stats(
    days: int = 7,
    session: dict = Depends(require_auth)
):
    """Get sleep statistics (average duration, quality, nights below goal)."""
    pid = session['profile_id']

    with get_db() as conn:
        cur = get_cursor(conn)

        # Get sleep goal from profile
        cur.execute("SELECT sleep_goal_minutes FROM profiles WHERE id = %s", (pid,))
        profile = cur.fetchone()
        sleep_goal = profile['sleep_goal_minutes'] if profile and profile['sleep_goal_minutes'] else 450

        # Calculate stats
        cur.execute("""
            SELECT
                AVG(duration_minutes)::FLOAT as avg_duration,
                AVG(quality)::FLOAT as avg_quality,
                COUNT(*) as total_nights,
                COUNT(CASE WHEN duration_minutes < %s THEN 1 END) as nights_below_goal
            FROM sleep_log
            WHERE profile_id = %s
              AND date >= CURRENT_DATE - INTERVAL '%s days'
        """, (sleep_goal, pid, days))

        stats = cur.fetchone()

    return SleepStatsResponse(
        avg_duration_minutes=round(stats['avg_duration'], 1) if stats['avg_duration'] else 0,
        avg_quality=round(stats['avg_quality'], 1) if stats['avg_quality'] else None,
        total_nights=stats['total_nights'],
        nights_below_goal=stats['nights_below_goal'],
        sleep_goal_minutes=sleep_goal
    )

@router.get("/debt")
def get_sleep_debt(
    days: int = 14,
    session: dict = Depends(require_auth)
):
    """Calculate sleep debt over last N days."""
    pid = session['profile_id']

    with get_db() as conn:
        cur = get_cursor(conn)

        # Get sleep goal
        cur.execute("SELECT sleep_goal_minutes FROM profiles WHERE id = %s", (pid,))
        profile = cur.fetchone()
        sleep_goal = profile['sleep_goal_minutes'] if profile and profile['sleep_goal_minutes'] else 450

        # Calculate debt
        cur.execute("""
            SELECT
                SUM(%s - duration_minutes) as debt_minutes,
                COUNT(*) as nights_analyzed
            FROM sleep_log
            WHERE profile_id = %s
              AND date >= CURRENT_DATE - INTERVAL '%s days'
        """, (sleep_goal, pid, days))

        result = cur.fetchone()

    debt_min = int(result['debt_minutes']) if result['debt_minutes'] else 0
    nights = result['nights_analyzed'] if result['nights_analyzed'] else 0

    # Format debt
    if debt_min == 0:
        formatted = "0 – kein Defizit"
    elif debt_min > 0:
        formatted = f"+{format_duration(debt_min)}"
    else:
        formatted = f"−{format_duration(abs(debt_min))}"

    return SleepDebtResponse(
        sleep_debt_minutes=debt_min,
        sleep_debt_formatted=formatted,
        days_analyzed=nights,
        sleep_goal_minutes=sleep_goal
    )

@router.get("/trend")
def get_sleep_trend(
    days: int = 30,
    session: dict = Depends(require_auth)
):
    """Get sleep duration and quality trend over time."""
    pid = session['profile_id']

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("""
            SELECT
                date,
                duration_minutes,
                quality
            FROM sleep_log
            WHERE profile_id = %s
              AND date >= CURRENT_DATE - INTERVAL '%s days'
            ORDER BY date ASC
        """, (pid, days))
        rows = cur.fetchall()

    return [
        {
            "date": str(row['date']),
            "duration_minutes": row['duration_minutes'],
            "quality": row['quality']
        }
        for row in rows
    ]

@router.get("/phases")
def get_sleep_phases(
    days: int = 30,
    session: dict = Depends(require_auth)
):
    """Get sleep phase distribution (deep, REM, light, awake) over time."""
    pid = session['profile_id']

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("""
            SELECT
                date,
                deep_minutes,
                rem_minutes,
                light_minutes,
                awake_minutes,
                duration_minutes
            FROM sleep_log
            WHERE profile_id = %s
              AND date >= CURRENT_DATE - INTERVAL '%s days'
              AND (deep_minutes IS NOT NULL OR rem_minutes IS NOT NULL)
            ORDER BY date ASC
        """, (pid, days))
        rows = cur.fetchall()

    return [
        {
            "date": str(row['date']),
            "deep_minutes": row['deep_minutes'],
            "rem_minutes": row['rem_minutes'],
            "light_minutes": row['light_minutes'],
            "awake_minutes": row['awake_minutes'],
            "deep_percent": calculate_phase_percent(row['deep_minutes'], row['duration_minutes']),
            "rem_percent": calculate_phase_percent(row['rem_minutes'], row['duration_minutes'])
        }
        for row in rows
    ]

# ── Import Endpoints ──────────────────────────────────────────────────────────

@router.post("/import/apple-health")
async def import_apple_health_sleep(
    file: UploadFile = File(...),
    session: dict = Depends(require_auth)
):
    """
    Import sleep data from Apple Health CSV export.

    Expected CSV format:
    Start,End,Duration (hr),Value,Source
    2026-03-14 22:44:23,2026-03-14 23:00:19,0.266,Kern,Apple Watch

    - Aggregates segments by night (wake date)
    - Maps German phase names: Kern→light, REM→rem, Tief→deep, Wach→awake
    - Stores raw segments in JSONB
    - Does NOT overwrite manual entries (source='manual')
    """
    pid = session['profile_id']

    # Read CSV
    content = await file.read()
    csv_text = content.decode('utf-8-sig')  # Handle BOM
    reader = csv.DictReader(io.StringIO(csv_text))

    # Phase mapping (German → English)
    phase_map = {
        'Kern': 'light',
        'REM': 'rem',
        'Tief': 'deep',
        'Wach': 'awake',
        'Schlafend': None  # Ignore initial sleep entry
    }

    # Parse segments
    segments = []
    for row in reader:
        phase_de = row['Value'].strip()
        phase_en = phase_map.get(phase_de)

        if phase_en is None:  # Skip "Schlafend"
            continue

        start_dt = datetime.strptime(row['Start'], '%Y-%m-%d %H:%M:%S')
        end_dt = datetime.strptime(row['End'], '%Y-%m-%d %H:%M:%S')
        duration_hr = float(row['Duration (hr)'])
        duration_min = int(duration_hr * 60)

        segments.append({
            'start': start_dt,
            'end': end_dt,
            'duration_min': duration_min,
            'phase': phase_en
        })

    # Sort segments chronologically
    segments.sort(key=lambda s: s['start'])

    # Group segments into nights (gap-based)
    # If gap between segments > 2 hours → new night
    nights = []
    current_night = None

    for seg in segments:
        # Start new night if:
        # 1. First segment
        # 2. Gap > 2 hours since last segment
        if current_night is None or (seg['start'] - current_night['wake_time']).total_seconds() > 7200:
            current_night = {
                'bedtime': seg['start'],
                'wake_time': seg['end'],
                'segments': [],
                'deep_minutes': 0,
                'rem_minutes': 0,
                'light_minutes': 0,
                'awake_minutes': 0
            }
            nights.append(current_night)

        # Add segment to current night
        current_night['segments'].append(seg)
        current_night['wake_time'] = max(current_night['wake_time'], seg['end'])
        current_night['bedtime'] = min(current_night['bedtime'], seg['start'])

        # Sum phases
        if seg['phase'] == 'deep':
            current_night['deep_minutes'] += seg['duration_min']
        elif seg['phase'] == 'rem':
            current_night['rem_minutes'] += seg['duration_min']
        elif seg['phase'] == 'light':
            current_night['light_minutes'] += seg['duration_min']
        elif seg['phase'] == 'awake':
            current_night['awake_minutes'] += seg['duration_min']

    # Convert nights list to dict with wake_date as key
    nights_dict = {}
    for night in nights:
        wake_date = night['wake_time'].date()  # Date when you woke up
        nights_dict[wake_date] = night

    # Insert nights
    imported = 0
    skipped = 0

    with get_db() as conn:
        cur = get_cursor(conn)

        for date, night in nights_dict.items():
            # Calculate sleep duration (deep + rem + light, WITHOUT awake)
            # Note: awake_minutes tracked separately, not part of sleep duration
            duration_minutes = (
                night['deep_minutes'] +
                night['rem_minutes'] +
                night['light_minutes']
            )

            # Calculate wake_count (number of awake segments)
            wake_count = sum(1 for seg in night['segments'] if seg['phase'] == 'awake')

            # Prepare JSONB segments with full datetime
            sleep_segments = [
                {
                    'phase': seg['phase'],
                    'start': seg['start'].isoformat(),  # Full datetime: 2026-03-21T22:30:00
                    'end': seg['end'].isoformat(),      # Full datetime: 2026-03-21T23:15:00
                    'duration_min': seg['duration_min']
                }
                for seg in night['segments']
            ]

            # Check if manual entry exists - do NOT overwrite
            cur.execute("""
                SELECT id, source FROM sleep_log
                WHERE profile_id = %s AND date = %s
            """, (pid, date))
            existing = cur.fetchone()

            if existing and existing['source'] == 'manual':
                skipped += 1
                continue  # Skip - don't overwrite manual entries

            # Upsert (only if not manual)
            # If entry exists and is NOT manual → update
            # If entry doesn't exist → insert
            if existing:
                # Update existing non-manual entry
                cur.execute("""
                    UPDATE sleep_log SET
                        bedtime = %s,
                        wake_time = %s,
                        duration_minutes = %s,
                        wake_count = %s,
                        deep_minutes = %s,
                        rem_minutes = %s,
                        light_minutes = %s,
                        awake_minutes = %s,
                        sleep_segments = %s,
                        source = 'apple_health',
                        updated_at = CURRENT_TIMESTAMP
                    WHERE id = %s AND profile_id = %s
                """, (
                    night['bedtime'].time(),
                    night['wake_time'].time(),
                    duration_minutes,
                    wake_count,
                    night['deep_minutes'],
                    night['rem_minutes'],
                    night['light_minutes'],
                    night['awake_minutes'],
                    json.dumps(sleep_segments),
                    existing['id'],
                    pid
                ))
            else:
                # Insert new entry
                cur.execute("""
                    INSERT INTO sleep_log (
                        profile_id, date, bedtime, wake_time, duration_minutes,
                        wake_count, deep_minutes, rem_minutes, light_minutes, awake_minutes,
                        sleep_segments, source, created_at, updated_at
                    ) VALUES (
                        %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, 'apple_health', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
                    )
                """, (
                    pid,
                    date,
                    night['bedtime'].time(),
                    night['wake_time'].time(),
                    duration_minutes,
                    wake_count,
                    night['deep_minutes'],
                    night['rem_minutes'],
                    night['light_minutes'],
                    night['awake_minutes'],
                    json.dumps(sleep_segments)
                ))

            imported += 1

        conn.commit()

    return {
        "imported": imported,
        "skipped": skipped,
        "total_nights": len(nights_dict),
        "message": f"{imported} Nächte importiert, {skipped} übersprungen (manuelle Einträge)"
    }